Instant cooked rice or frozen cooked rice is produced from cooked gelatinized rice by drying or quick freezing. It is convenient since it becomes eatable with heating by pouring hot water, by immersing in hot water or by using a microwave oven. Recently, with technology innovation, instant cooked rice or frozen cooked rice can have texture and taste quite similar to those of actually cooked rice, cooked fried rice, or cooked pilaf, and therefore, the number of products and the amount of sales have been both increased.
One of important aspects in producing such products is to make cooked rice into individual grains, that is, to loosen cooked rice not to become a lump state.
Cooked rice tends to become an agglomerated state (lump state) as the surfaces of the rice grains are gelatinized through cooking to become highly sticky, whereby the rice grains bind together. When producing instant cooked rice, for example, if cooked rice is in an agglomerated state, the center portion of the agglomerated state rice is hard to dry, resulting in insufficient or uneven drying. Even if the cooked rice can be dried, the bound portion is hard to be reconstituted in hot water and is poor in texture. Further, when producing frozen cooked rice, quick and even freezing cannot be made, and after produced, it is hard to unfreeze.
It is important to loosen such cooked rice into individual grains, and most of conventional cooked rice loosening methods loosen the cooked rice mechanically by stirring up it using a radially shaped rotary vane or the like. However, those loosening methods applying a mechanical force using such rotary vane have disadvantages that rice grains are smashed and the loosening effect cannot be provided over the whole cooked rice fed in.
The present invention provides a cooked rice loosening method using air. Here, prior an technology for loosening cooked rice using air is disclosed in Patent Document 1 and 2. These prior art documents respectively disclose a method in which cooked rice is dropped down, and strong air is applied to the dropping cooked rice to blow it off. However, in this method, the time of applying the strong air to the cooked rice is short, so that a sufficient effect cannot be expected.